Technical Field
The following disclosure relates to a white key of a keyboard instrument.
Description of the Related Art
Patent Document 1 (Japanese Patent Application Publication No. 2007-139885) discloses white and black keys each including: an upper wall elongated in a front and rear direction; and a pair of side walls extending downward respectively from right and left edges of the upper wall and each elongated in the front and rear direction, and the upper wall and the pair of side walls are formed of resin in one piece so as to have an inner space opening downward. In this example, the upper wall and the side walls have the same thickness.
Patent Document 2 (Japanese Unexamined Utility Model Application Publication No. 6-60887) discloses a white key including: an upper wall elongated in a front and rear direction; and a pair of side walls extending downward respectively from right and left edges of the upper wall and each elongated in the front and rear direction, and the upper wall and the pair of side walls are formed of resin in one piece. This white key includes: a narrow segment which is narrow in width in a lateral direction and formed with an inner space opening downward; and a wide segment which is wide in width in the lateral direction without having an inner space. In this white key, a gate for molding is provided in an intermediate portion of the narrow segment of one of the pair of side walls, whereby the thickness of the side wall not provided with the gate is greater than that of the side wall provided with the gate in the narrow segment. A hot molten resin material is poured into the narrow segment, and this resin material is cooled first in the side wall not provided with the gate and then cooled in the side wall provided with the gate. Thus, a larger amount of resin is poured into the side wall not provided with the gate than into the side wall provided with the gate, such that the side walls require the same amount of time for cooling and solidifying. This technique prevents the white key formed of resin from warping.